curl --request POST \
  --url https://{host}/v1/me/favorites \
  --header 'Authorization: Bearer <token>' \
  --header 'Content-Type: application/vnd.api+json' \
  --data '
{
  "data": {
    "type": "favorites",
    "relationships": {
      "watch": {
        "data": {
          "type": "watches",
          "id": "91827"
        }
      }
    }
  }
}
'

const options = {
  method: 'POST',
  headers: {Authorization: 'Bearer <token>', 'Content-Type': 'application/vnd.api+json'},
  body: JSON.stringify({
    data: {
      type: 'favorites',
      relationships: {watch: {data: {type: 'watches', id: '91827'}}}
    }
  })
};

fetch('https://{host}/v1/me/favorites', options)
  .then(res => res.json())
  .then(res => console.log(res))
  .catch(err => console.error(err));

<?php

$curl = curl_init();

curl_setopt_array($curl, [
  CURLOPT_URL => "https://{host}/v1/me/favorites",
  CURLOPT_RETURNTRANSFER => true,
  CURLOPT_ENCODING => "",
  CURLOPT_MAXREDIRS => 10,
  CURLOPT_TIMEOUT => 30,
  CURLOPT_HTTP_VERSION => CURL_HTTP_VERSION_1_1,
  CURLOPT_CUSTOMREQUEST => "POST",
  CURLOPT_POSTFIELDS => json_encode([
    'data' => [
        'type' => 'favorites',
        'relationships' => [
                'watch' => [
                                'data' => [
                                                                'type' => 'watches',
                                                                'id' => '91827'
                                ]
                ]
        ]
    ]
  ]),
  CURLOPT_HTTPHEADER => [
    "Authorization: Bearer <token>",
    "Content-Type: application/vnd.api+json"
  ],
]);

$response = curl_exec($curl);
$err = curl_error($curl);

curl_close($curl);

if ($err) {
  echo "cURL Error #:" . $err;
} else {
  echo $response;
}

import requests

url = "https://{host}/v1/me/favorites"

payload = { "data": {
        "type": "favorites",
        "relationships": { "watch": { "data": {
                    "type": "watches",
                    "id": "91827"
                } } }
    } }
headers = {
    "Authorization": "Bearer <token>",
    "Content-Type": "application/vnd.api+json"
}

response = requests.post(url, json=payload, headers=headers)

print(response.text)

{
  "data": {
    "type": "favorites",
    "id": "5521",
    "attributes": {
      "createdAt": "2026-09-22T17:04:00.000000Z",
      "availability": "available"
    },
    "relationships": {
      "watch": {
        "links": {
          "related": "https://api.wristler.eu/v1/me/favorites/5521/watch"
        }
      }
    },
    "links": {
      "self": "https://api.wristler.eu/v1/me/favorites/5521"
    }
  }
}

{
  "data": {
    "type": "favorites",
    "id": "5521",
    "attributes": {
      "createdAt": "2026-09-22T17:04:00.000000Z",
      "availability": "available"
    },
    "relationships": {
      "watch": {
        "links": {
          "related": "https://api.wristler.eu/v1/me/favorites/5521/watch"
        }
      }
    },
    "links": {
      "self": "https://api.wristler.eu/v1/me/favorites/5521"
    }
  }
}

{
  "errors": [
    {
      "status": "404",
      "code": "watch_reserved",
      "title": "Not Found",
      "detail": "<string>",
      "meta": {},
      "source": {
        "pointer": "/data/attributes/reference",
        "parameter": "<string>"
      }
    }
  ],
  "jsonapi": {
    "version": "1.0"
  }
}

{
  "errors": [
    {
      "status": "404",
      "code": "watch_reserved",
      "title": "Not Found",
      "detail": "<string>",
      "meta": {},
      "source": {
        "pointer": "/data/attributes/reference",
        "parameter": "<string>"
      }
    }
  ],
  "jsonapi": {
    "version": "1.0"
  }
}